The long term objective of this proposal is to understand the mechanism responsible for reactivating latent oral herpes simplex virus type I (HSV-1). The proposed studies are based on the hypothesis that ultraviolet light-induced cell proteins enhance virus reactivation by binding the promoter of the latent- associated transcripts gene, the only transcriptionally active site during latency. The specific aims are: (1) to identify the DNA region of herpes simplex virus type 1 that binds UV-induced cell proteins using mobility shift assay; (2) to delimit the DNA binding site identified in Specific Aim 1 by DNase I footprinting; and (3) to identify, isolate, and sequence the cellular gene that encodes the DNA binding protein identified in Specific Aim 1.